Circuit interrupter



Feb. 10, 1948.

H. L. RAWLINS CIRCUIT INTERRUPTER Filed May 27, 1943 5 Sheets-Sheet 1 INVENTOR Herbe/* ./Qdw/Yns.

Peb. 1o, 194s. H, L RAWUNS 2,435,844

CIRCUIT INTERRUPTER y INVENTOR HerberfL-Eaw/f'05. l

ATTORN Y Patented Feb. l0, 1948 UNITED STATES OFFICE CIRCUIT INTERRUP'IER Herbert L. Rawlins, Pittsburgh, Pa., assigner to Westinghouse Electricyorporaticn, East Bittsburgh, Pa., a corporation of Pennsylvania,

Application May 2 7, 1943 Serial No. 488,621

(Cl. 20G-114) 23 Claims. 1.

This invention relates generally to electric circuit interrupters, and more specically to high-voltage fuses of the dropout or indicating types.

This invention constitutes a continuation-in- -part of the subject-matter of my copending application Serial No. 319,896, led February 20, 1940, on Gas blast circuit interrupters, now Patent No. 2,343,422, issued March 7, 1944, and assigned to the same assignee of this invention.

High-voltage fuses are used in many locations where it is necessary that they be entirely enclosed so that there is no external display when the fuse blows, and so that they are completely protected from the surrounding atmosphere, It is also desirable in many such instances that the fuse be mounted so as to automatically 4drop out of the circuit after blowing to introduce an air gap and to give a readily visible indication of the blown condition. For certa-in purposes, it may suffice merely to provide an indication of the blown condition of the fuse, where it is not necessary or desirable to introduce an air gap in the circuit.

Accordingly, one object of this invention is to provide a totally enclosed dropout fuse which remains totally enclosed during and after blowing of the fuse and movement of the fuse out of the Circuit.

Another object of this invention is to provide a novel type of dropout fuse wherein a predetermined fluid pressure is generated by the arc formed when the fuse blows irrespective of the current value of the arc, and this pressure causes the dropout action of the fuse.

Another' object vof this invention is to provide a novel totally enclosedfuse construction having means movable outwardly relative to the fuse to a projecting position in response to blowing of the fuse, without opening the fuse enclosure to the atmosphere.

Another .object of this invention is to provide a novel totally enclosed fuse .construction having means mechanically movable outwardly to a prof jecting position with respect to the. fuse in re.- sponse to blowing of the fuse, without opening the fusekr enclosure to the atmosphere. Another object of this invention is to provide a fuse with novel means biased outwardly ,of the fuse for movement relative to the fuse tube without open` ine the tube to atmosphere, which means is normally restrained by ,the fusible means so that it moves outwardly in response to blowing of the fuse.

Another .object of this invention is to provide r a 55 fuse of the type describedA wherein a movable means outwardly biased with respect to the fuse'l tube isfnormally restrained by a mechanical connection which is rendered ineiective upon blowing of the fuse.

These and other objects of this invention will become more apparent from the following de,- scriptionofpreferredembodiments thereof, when taken in connection with the aQQmDanyQ-f' drawings, in which:

Figure l is aside elevation view illustrating one embodiment ofthe invention, with part of Fig. 3`v is a View similar to Fig,- 2, but showing;

another modified construction;

Fig. 4 is an elevational view` of a modied fuse and support, with theV upper end of the fuse in section; f

Fig. 5 is an elevational view of the upper endv of a modiied'form of fuse, with the upper ycontact construction and part of the fuse structure being inSeCtOn.: i

Fig. 6- is a, view of the construction shown in Fig. 5, with the upper end of the fuse shown in section and with the par-tsin a different position;

Fig. 7- is a section of the-upper end ofr a modied form of fuse;

Fig. 8 is a section of the upper end of the fuseshown in Fig. r'7, with the parts in the position theyv assuinewhen the fuse has blown;

Fig. 9 is a section of the upper end of another modified form of fuse;

Fig. 10 isa section of the upper end of the fuse shown in-Fig. 9, `with the par-ts in t-he position they assume whenV the-fuse has blown;

Fig. 1-1 is a'sect-ional view of the'upper end of anotherlnodiiied form of fuse;

Fig. l2 is a section of the upper end of the fuse shown in Fig. 1*,1, with the parts shown in the position they .assume when the use has rblown;

Fie- 1.3 is a ,section of the upper @mi of Still another modified form of `fuse;

Fig. A1i is a section ,of the upper end of the fuse Shown in Fie,- ,131 but with the parts Shown in the, DQS'll $11.95. @Ssul When the fuse .has blown.;

rie. A,1-.5 is a longitudinal sectional .View of Stil-l another modiied form of fuso .capable .of keine mounted 'in a manner similar to .the fuse A shown inizi;

Fig. 16 is a longitudinal section of the upper end of a fuse similar to that shown in Fig. 15, but slightly modied in form; and

Fig. 17 is a longitudinal section of the upper end of a fuse similar to those shown in Figs. and 16, but illustrating still another modication of the invention,

In Fig. 1, there is illustrated a mounting for a fuse which may be utilized for supporting any desired type of fuse. This mounting is designed so that, upon blowing of the fuse, the fuse tube terminals are released from engagement with respect to at least one line contact, and the fuse tube proper is supported so that it is movable in response to blowing of the fuse to move at least one of its terminals out of engagement with respect to at least one of the line contacts.

As shown in Fig. 1, a pair of insulators 4 and 6 are secured in spaced relation on a supporting member 2. The upper insulator 4 is provided with a substantially L-shaped resilient contact and terminal 8, one leg of which is secured to the cap of insulator 4, as by the machine screws I0, and the other leg of which extends substantially horizontally and is provided with an aperture for receiving a projection II on the upper end of the fuse. The outer end of the horizontal leg of terminal member 8 is upwardly turned as at I2, for a purpose to be described. The fuse is provided with a tubular enclosure I8 of any desired insulating material, such, for example, as ber, porcelain or the like. The fuse tube is provided with a terminal cap 9 at the upper end thereof and with a terminal ferrule I9 at the lower end thereof. The upper fuse terminal cap may be provided with a pair of outwardly extending spaced supporting arms I3 for pivotally supporting therebetween a release lever l5. The lever i5 is apertured, as shown, for the insertion of a hookstick or other operating member, and, as appears from Fig. 1, is adapted to release the upper end of the fuse from contact member 8 when the lever I5 is rotated in a clockwise direction about its'pivot. Such movement of release lever I5 acts to raise the outer end I2 of contact 8 out of engagement with projection IIl on the upper fuse terminal cap 9. With the fuse pivotally mounted at its lower end, it is obvious that the fuse may be moved in a generally counterclockwise direction when at an open circuit position to become reenegaged with contact member 8, since the projection II on the fuse will engage with the outer upturned end l2 of the contact 8 and cam the same upwardly, to permit the projection II to ride along the undersurface of contact 8 until it becomes aligned with the aperture therein, when it will be latched in the position shown in Fig. 1. The vertical arm of contact 8 may serve as a terminal portion for the connection ci a line conductor thereto.

The lower` fuse terminal ferrule I9 is provided with a pair of spaced and inwardly extending arms I1 for pivotally supporting therebetween, as by a pivot pin 42, an intermediate portion of a supporting lever 64. The inner end of lever 44 is provided with lower opposed trunnions 46 adapted to be received in notches provided in the sides of a split contact member I4 secured to the outer end of lower insulator 6. Contact i4 is provided with an integral downwardly extending terminal portion I6 for connection of a line conductor thereto. The inner end of lever 44 is also provided with upper opposed positioning lugs 48 adapted to properly position the lever with respect to contact I4, and also is provided with intermediate stop lugs 50 adapted to engage con- Aformed to extinguish the same.

cave stop portions 52 provided on the contact, as will be hereinafter described. A flexible conductor 38, forming part of the circuit through the fuse, is adapted to extend out of the lower end of the fuse tube and over a lateral projection 54 on the outer end of supporting lever 44 to be secured to the lever, as by a thumb nut 56.

As previously stated, any desired type of fuse may be supported in engagement with a pair oi line contacts by the means described above. However, the fuse illustrated in Fig. 1 is of the type which utilizes a source of compressed gas which is released upon blowing of the fuse, and the released gases are directed through the arc This fuse construction is more particularly described and claimed in'my copending application referred to above.

"In this" fuse construction, a tubular member 20 is provided within fuse tube I8 adjacent the upperend thereof, and has an end plug 22 secured'in the upper end thereof, as by welding, brazing or the like. The end closure plug 22 is provided with a reduced projection 24 for extension through the opening 26 in upper -iuse terminal cap 9 to cooperate with a clamping disc 28 for securing this rei'ill unit in operative position Within fuse tube I8. End closure plug`22 is provided with a substantially central bore extending to the outer end of projection 24, and the bore may be sealed by the threaded sealing plug 30. The lower end of tubular member 20 is provided with an aperture which is closed by a fusible plug 32. Fusible plug 32 is, in turn, connected by a short calibrated fusible section 34 to a sleeve 36 on the upper end of ilexible conductor 38. Tubular member 20 is provided with an insulating throat member 40 to provide a restricted or a Venturi gas passage through which gases released from tubular member 20 pass upon melting of fusible plug 32. Tubular member 20 is adapted to be lled with a gas under pressure, such, for example, as air or the like, and then sealed by plug 3U.

In operation, when the current through the fuse exceeds a predetermined value, the fusible section 34 melts and an arc is struck to the fusible plug 32. Plug 32 will, in turn, melt and thereby provide an opening in the lower end of tubular member 2o through which the stored compressed gas may escape. When the fusible section 34 and plug 32 melt, an arc is struck from the adjacent portion of tubular member 20 to the sleeve 36 on flexible conductor 38. Obviously, gases escaping from the lower aperture in tubular member 20 will necessarily be directed through the arc drawn, and will also tend to expel flexible conductor 38 through the Venturi passage in insulating throat member 4D. It should also be noted that, after the fuse has blown and interrupted the circuit, it may be renewed by removing the blown refill unit and inserting a new one, by merely removing clamping disc 28 to permit the refill unit to drop through the open end of the fuse tube. The new rell unit may be inserted through the open end of the fuse tube and secured in position by clamping disc 28. Thereafter the conductor 38 thereof may be secured to supporting lever 44 in the manner shown in Fig. 1.

When the fuse blows to interrupt the circuit as described above, flexible conductor 38 will be released within fuse tube I8, and accordingly will no longer support the outer end projection 54 of supporting lever 44. The fuse tube and lever are cesses 52 provided on contact i4. Fuse tube |8f is.l

then free to rotate abouti pivots 42 and 4S. in. a. clockwise direction outwardly and away.y fromzupper contact 8`` to thereby introduce. alarge. air. gap: in the circuit.

The release of flexible conductor 38'. may be els...

fected by the gas pressure developed within the.

fuse. Howeven. todo' this, the fuse should be of the type, such as that shown inFig. 1, wherein a predetermined gas pressure is built up within the fuse whenever the fuse blows, which pressure is independent of. the valueof. the current interrupted in order to obtain reliable operation. To obtain release by pressure, ilexible conductor 38 may have secured thereto a relatively rigid piston-like member 58 (Fig. 2) proportioned to closely t in an aperture in a terminal cap` 59 secured-to the lower end of fuse tube i8. Thev piston member 58is preferably provided with an upper flange portion 60 within the .fuse tube to limit downward movement thereof'. It will be obvious that, withthe construction shown in Fig. 2, the gas pressure developed within the fuse tube will positively move piston member 58, and consequently the lower end of flexible conductor 36, downwardly, to permit the fuse tube to be disengagedY from its upper contact 8. The use of such a construction prevents possible fouling of the lower opening through which iiexible conductor 38 extends, and positively insures movement of the conductor to release supporting lever 44 and permit the fuse to drop out of the circuit. Moreover, it will be observed that, with this construction, the fuse` is entirely enclosed at all times, so as to be entirely protected from the atmosphere, and to prevent the emission of ame or ionized' gases from the fuse to the atmosphere.

Fig. 3 illustrates a slightly modied form of connectionV between a supporting lever l'B, generally similar tothe supporting lever lid described in connection with Figs. 1 and 2, and adapted to be supported on a contact, similar to the contact I4 of Fig. l, but with the fuse being entirely7 enclosed at all times, asin the embodimentl of the invention shown in Fig. 2. The fuse tube in this embodiment of the invention is provided with a lower terminal cap 612 having any eccentric or offset' opening` provided with a bushing 5d, through which passes the lower end of iiexible conductorv 38 to be secured to terminall cap 62, asby a thumb nut 66. End cap 62 is provided with a centralaperture for receiving a piston member 68 proportioned to relatively closely slidably fit Within the aperture through terminal cap'A 62. Pistonv 68 is provided with a flange 'l0 within the fuse tube to limit downward movement of thev piston. In the normal position or the fuse, the lower end' of piston G8 is adapted to engage one arm of a bell-crank lever 12 pivoted as at 'M between spaced, depending supporting ears integral with fuse terminal cap 612. The other arm of bellcrank lever 12 is formed into a hook-shape at its outer end for engagement with a pinr 16, extending betweenthe sides 'I5 of the split outer end of supporting lever 18; Supporting lever 18, similar to the lever 44- previously described, is provided' with positioninglugs 80, trunnions- 82 and stop lugs 8`4`- similar tothe corresponding lugs and;

by a flexible", shunt. 86' secured to the lever and# terminal cap; as by thescrews 88'. Lever 1811s.

. mounted". between spaced. pivot supporting arms;

911` integral' with lower fusev terminal carp 62g as; bythe pivot pin= 92;

In the operation of this embodiment of: the im vention.- itis apparent that"` normally lever 18 isf' latched against movement relative to fuse tube i8", by a positive latching means 12; '16, whichy is independent of iiexible conductor 38; and, there-- fore, independent of thefusibl'e means within thefusetube. Lever 181 and fuse tube l8= are released for relative movementupon blowing of the fuse solelyv by the gas pressure developed within the fuseftub'e acting upon piston member IG8, which is movedl outwardly thereby, torotate bell-crank' lever 'l2A in a clockwise direction about its pivot., 14'outof latching engagementwith respect to pin`- 'l-Eon lever 18. The'ffuse' tube may then drop-down and out of the circuit asdescrib'ed in connection with the embodiment ofthe invention show-n in Fig. 1.

The fuse structures shown in Figs. 2 and 3 pro'-V vide totally enclosed'fuse constructionswhich are`v adapted to drop outLof their associated circuit, or disengage at least one'- terminal of the fuse from a line contact, to insert a relatively largel air gap in the circuit. Furthermore, the dropout movement of such an enclosed" dropout' fuse is ini tiated by gas pressure developed within the fuse" tube, or the gas pressure maybe utilizedto release" a latchfholding' the parts in the circuit. Furthermore, this pressure utilized in the dropout opera l tion in these improved fuse constructions is envtirely independent ofthe valuecf the current interrupted, and hence may be of a predetermined value which will give eicient and reliable drop' out operation under allv conditions. The particular fuse construction illustrated in Fig. 1 provides a quantity of gas when the fuse blows which is predeterminedv by thev amount ofA gas stored in container 20; and which quantity is independent of the current values interrupted by the fuse. Furthermore, this gas` not only is used to extinguish and attenuatethearc drawn when the fuse blows, but is also used to build upa pressure within the fuse tube to reliably operate means for releasing l the fuse from its associated circuit. Also, the: source Vof gas and fusible portion of these fuse constructions are designed to beL replaceable as a unit within a fuse tube, and to be releasably secured therein by relatively simple means.

In the embodiment ofthe invention illustrated in Fig. 4, a fuse 94 is provided comprising an insulating tubular enclosure 96 which maybe of any desired insulating material, such as fiben. porcelain or the like; Terminal caps and |00 are secured over the outer ends of fuse tube 96 in any desired manner, such, for example, as by crimping portions ofthe terminal cap into the material of the fuse tube". The lower terminal.A cap iil is` provided with oppositely extenelingv iiat-sided trunnions I'El2v for reception in keyhole slots IM provided in spaced contact arms 10S, which may-in turn be supported on an insulator 1(i, similar to contact I4, as shown in Fig. 1.

A toggle lever` |08 is4 pivotally supported on upper fuse terminal cap- 98 by a pair of spaced supporting members H2 integral with Athe terminal cap, and carrying a pivot pin IIB at their outer ends for pivotally supporting toggle lever |08 therebetween. The toggle lever is provided. at one end with a nose l I4 adapted, in the closed` circuit position of the fuse, to engage an indentationprovided in a resilient contact member |I6. Contact member ||6 may be formed and supported on a line insulator in a manner similar to contact member 8, as shown in Fig. 1. Normally toggle lever |08 is prevented from rotating about pivot pin by a low melting point solder ||8 securing the other end of the lever to substantially the central portion of fuse terminal cap 98.

Within fuse tube 96 there is provided a conductor wire |20 secured, as by soldering or the like, to terminal caps 98 and |00 to complete the circuit within the fuse. For low current ratings, conductor |20 may be of fusible material so that it melts on overload. However, for high current ratings, conductor |20 maybe arranged in parallel with a calibrated fusible member, as in my previously mentioned copending application. In either case, conductor |20 will fuse and strike an arc to upper termin-al cap 98. A cup-shaped support |22 is secured to the inner side of terminal cap 98 for supporting in proximity to the end wall of the cap, over the area occupied by solder ||8, heat-producing material |24. The material |24 may be any desired combustible material capable of producing a relatively large quantity of heat When ignited, such as Thermite or the like.

In the operation of the fuse shown in Fig. 4, it will be apparent that, upon an overload in the circuit, conductor |20 will melt and an arc will be struck in proximity to heat-producing material |24 to ignite this material, and thereby produce relatively large amounts of heat which will be conducted through the end wall of terminal cap 98 to melt solder |8, and release toggle lever |08 for movement about its pivot ||0. Toggle lever |08 will be moved in a counterclockwise direction about its pivot |0 by the force exerted downwardly by resilient contact ||6 acting on the nose ||4 of toggle lever |08. This will not only cause counterclockwise movement of toggle lever |08 about its pivot ||0, but will cause the pivot point to move to the right. as viewed in Fig. 4, and thus cause fuse 94 to rotate in a clockwise direction about its trunnions |02 and drop out of the circuit.

It will be observed that the fuse described above and shown in Fig. 4 of the drawings is entirely enclosed at all times, and is released for movement out of its associated circuit by heat conducted through one of its terminal caps from heat-generating means ignited in response to blowing of the fuse, to generate a predetermined quantity of heat within the fuse.

The fuse |26 illustrated in Figs. 5 and 6 of the drawings is adapted to be pivotally mounted at its lower end in a manner like the fuse shown in Fig. 4. Fuse |26 is provided with an upper terminal cap |28 secured to the upper end of the fuse tube, and this cap is provided with a flexible end wall |30 which normally does not extend above the side walls of the cap and preferably is concave in form, as shown in Fig. 5. A conductor |32 of fusible material, which may be connected in parallel with a fusible element like conductor |20 shown in Fig. 4, is connected to the central portion of flexible end vwall |30 of the terminal cap, to normally maintain the wall in the concave form shown in Fig. 5. A disc |34,

which may be of insulating material such as fiber,

or the like, is adapted to be seated on the outer end of the fuse tube and to confine betweenv disc |34 and end wall |30 of the terminal cap, a pre- 8 e determined charge of combustible explosive ma; terial, such, for example, as gunpowder or the like.

It will be apparent that, when conductor |32 melts to establish an arc in the space between disc |34 and end wall |30 of the upper fuse terminal cap, the explosive material will be ignited and will force end wall |30 to the convex form shown in Fig. 6, wherein it projects above the side Walls of terminal cap |28. This will give a clearly visible indication of the blown condition of the fuse, and may be utilized to operate latch release means for causing the fuse to drop out of the circuit.

The fuse |26 may be used with an upper contact and latching mechanism |36 to enable the same to drop out of the circuit. This contact and latching mechanism is more particularly described and claimed in the copending application of H. L. Rawlins and John J Mikos, Serial No. 428,710, filed January 29, 1942, now Patent No. 2,403,121, issued July 2, 1946, and assigned to the same assignee as this invention. Accordingly, for a more complete description of the construction and operation of the contact and latch mechanism |36, reference is hereby made to the aforesaid patent of Rawlins and Mikos. In general, this Contact and latch mechanism is pro, vided within a protective hood |38 adapted to be mounted on a line insulator, such as the insulator 4 shown in Fig. 1 of the drawings. Beneath hood |38 there is supported a contact latch lever |40 by means of a cross-pin |42 secured in hood |36, and received in a slot |44 provided in latch lever |40. A coiled compression spring |46 reacts between lever |40 and hood |38 to bias the lever in a generally counterclockwise direction about supporting pin |42. A release lever |48 is pivoted on latch lever |40 by a pivot pin |49, and the release lever is provided with an arm adapted to normally engage an abutment |50 integral with hood structure |38. Release lever |48 has a nose |52 overlying end Wall |30 of fuse terminal cap |28. Lever |40, which is generally rectangular in form, has opposite sides thereof provided with notches |54 for receiving projections |53 provided on a fixture |58 secured to fuse terminal cap |28. The fixture |58 is provided with a hook-eye aperture, as shown, for manual manipulation of the fuse.

The operation of mechanism |33 upon blowing of fuse |26 will be, in general. that the reversal of curvature of flexible end wall |30 of terminal cap |28 will cause the end wall to engage release lever |48 and move it in a counterclock- Wise direction relative to latch lever |40, until the release lever disengages abutment |50 on hood |38. This will release spring |46 to cause counterclockwise pivoting of latch lever |40 relative to supporting pin |42, and move fuse |26 to the position shown in Fig. 6. When the fuse has attained the position shown in Fig. 6, it has sufncient kinetic energy, and is positioned so as to be acted upon by the force of gravity to move to a fully open circuit position entirely disconnected from at least one line contact. It will be observed that fuse |26 remains entirely enclosed at all times, and that dropout action is initiated by the bulging upwardly of end wall |30 of the upper fuse terminal cap |28.

-In Figs. 7 and 8, there is illustrated a fuse |60 including a fuse tube |62 of insulating material adapted to have both ends thereof closed. The lower end of fuse tube |62 may be closed by a terminal cap similar to the cap-|00 shown provided with a terminal cap |64 secure-d to the fuse tube in any desired manner. vTerminal cap :|64 is provided with a substantially centrally lo- .cated aperture `for `slidably receiving a plunger' |1616, vthe inner endof which is secured to the central portion of a flexible diaphragm |68. Flexib'le diaphragm |68, in the embodiment of the invention illustrated, is preferably made of a thin flexible metal, and is `secured at its periphery to the side wall of terminal cap |64 in any desired manner, such, for example, as by soldering or the like. As shown, plunger V|68 is provided with a reduced inner end portion extending through a central aperture in flexible diaphragm |68, and is secured to the diaphragm as by soldering or welding. Plunger |66 is maintained with the major portion thereof within fuse tube 1562 and terminal cap |64, 'by conductor |16, which is sen cured to the inner end of the plunger. Conductor |10 may be of fusible material and connected to the lower terminalcap of fusetube |62, or it may be connected to the strain element for a fusible .member within the lower portion of fuse tube |62. A spirally coiled spring |12 hasthe outer lcoil thereof seated on the upper end of fuse tube |62, and the inner coil thereof closely surrounds the reduced extension of plunger |56 be low diaphragm |68, to bias the central part of the diaphragm and plunger |66 in a direction upwardly, relative to the -fuse tube,

`It will be observed that the iiexible diaphragm |68 seals the upper end of fuse tube |52, even when it is exed to the position shown in Fig. 8. In Athe operation of this embodiment of the invention, when the fuse blows, conductor mi is no longer effective to maintain plunger yIGS at the position shown in Fig. '7, and spring H2 is thus freed to move plunger |66 and the diaphragm to the position shown in Fig. 8. With the plunger |66 at'the position shown in Fig. 8, a readily `:visible indication is provided to indicate the blown condition of the fuse. The fuse shown in Figs. 7 and 8 may be mounted in the same manner as the `fuse |26 shown in Figs. 5 and 6, with release lever |48 overlying top terminal cap |54 `so as to be actuated to release `the contact and latch mechanism ISSby movement of plunger |66 from the position shown in Fig. y7 to that shown in Fig. 8.

In Figs. 9 10, there is illustrated a fuse having a plunger .|89 normally held in the retracted .position shown in Fig. `9 and movable to the extended position shown lin Fig. l0 upon blowing of the fuse to give a readily visibleindication of the blown condition of the fuse, or for actu ating release mechanism, such as the mechanism |36shown in Figs. `5 .and 6. The fuse |14 shown in Figs. 9 Aand l0 includes an outer tube |16 of insulation material having a top Iterminal cap |18 secured over the upper end thereof in any desired manner. Plunger ,|83 is adapted to slide through a central aperture provided in Ptop terminal cap |18, and is provided at its inner end with an outwardly extending stop ange |782. A. generally cup-,shaped housing |54 has the open end thereof secured to terminal cap |78 within fuse'tube I'll to .form .housing .for plunger ld. Plunger ist is preferably of lhollow construction for receiving a coiled compression sprin. |85 therein which normally acts to bias the plunger outwardly to the position shown in Fig. l0. wherein ilange |82 on the plunger engages the cover Cto limit outward movement of the plunger beyond this position. YPlunger |80 is normally' held retracted in the position shown in Fig. 9 by low melting point solder |88 joining ange 82 to the bottom wall of housing Idil. A second generally cup-shaped housing IS@ is provided over the inner end of housing |35 for containing heatproducing material |92, which may be like the material |24 described above in connection with the embodiment of the invention shown in Fig. 4. A conductor |93, which may be like the conductor |26, also described in connection with the embodiment ofthe invention shown in Fig. 1i, and may be connected in the same manner as conduetor |25), is secured at its upper end to the bottom wall of housing |84 and extends through housing |99 and the heat-producing material Atherein to be connected to the terminal cap at the end of fuse tube'l 16.

:In 'the operationof the embodiment of the invention shown in Figs. 9 and 10, it will be apparent that when conductor |93 is melted upon blowingofthe fuse, an arc will be struck in proximity to heat-producing material 92 to heat the lower end wall of housing |8l, and thereby melt solder r|88 and release plunger |89 for movement by spring I 86 to the position shown in Fig. lO. l-lere again, it Will ybe noted that theiuse tube is cornpletely closed at al1 times, but the plunger itil provides a means forgiving an external indication of the blown condition of the fuse, or for releasing a latch mechanism such as that disclosed in Figsf5 and 6.

In Figs. 11 and `12, there is disclosed another modiiication `of a means for providing an external indication for a fuse, while the fuse remains closed at all times, which means say, if desired, be usedto operate a latch release mechanism of the type shown in Figs. 5 and 6. Fuse |93 shown in Figs. 11 and 12 includes an outery fuse tube wt of insulating material, having a top terminal cap z|98 secured thereto in any desired manner. A leaf spring Zilii is secured to the outside of terminal cap |98 in any desired manner, such, for example, as by a rivet 232|. Spring 2M) is strained-in a manner such that it will normally occupy the position shown in Fig. 12, but it is vnormally maintained against the outside `of terminal cap |98, as shown in Fig. 1l, by low meltingpoint vsolder 2M. Within fuse tube |86 in proximity with the inner surface of terminal cap |98 and located about the area occupied by solder 264 `on the exterior of the terminal cap, there is provided a cup-shaped holder 238 forvheat-producing material 2id, sirnilar to the material I 24 and IS?, previously described. kHolder 208 is maintained in position by an integral extension 206 received between the end of fuse tube |35 and terminal cap idd. A conductor 212, similar to the conductors 525| and |33 previously described, extends through holder 2&8 and heat-producing material 2id, to be secured to terminal cap |98.

The operation ofthe embodiment of the invention shown in Figs. 1l and 12 will be obvious, since it is much like that-shown in Figs. 9 and l0. When conductor 2|2 melts to form an arc in proximity to heat-producing material 2id, the heat therefromwillbeconducted through terminal cap |98 to melt solder 2nd and release the outer end of spring 2M and permit it to move tothe position shown in Fig. 12. It will be observed that this structure comprises a fuse which is completely enclosed'at all times, similar to the embodiments of the invention previously described.

.In Figs. 13 and 14, there is shown a fuse conupwardly projecting portion 238,

' struction much like that of Figs.` 7 and 8, except that instead of using a ilexible diaphragm, a flexible bellows-like arrangement is utilized to seal the upper end of the fuse. Fuse 2I4, like the fuse illustrated in Figs. 'l and 8, is provided with an outer supporting tube 216 of insulating material, having an upper end terminal cap 2I8 secured thereto in any desired manner. The terminal cap 218 is provided with a central aperture for slidably receiving a plunger 220 secured at its inner end to a plate 222. Plate 222 is biased upwardly by a coiled spiral spring 224, and the opening in terminal cap 2I8 is sealed by a flexible bellows-like member 228, secured to the terminal cap and to plate 222. Bellows 228 may be of any desired material, being shown as of metal, but it may be of other ilexible material, such as rubber, fabric or the like. A conductor 226, similar to the conductor |16 previously described, is secured to the inner side of plate 222 for normally maintaining plunger 22D at the retracted inner position shown in Fig. 13.

In the operation of the embodiment of the invention shown in Figs. 13 and 14, when conductor 226 is released upon blowing of the fuse, spring 224 is released to move plunger 228 to the projecting position shown in Fig. 14. This movement of plunger 220 may be utilized to merely give a visual indication of the blown condition of the fuse, or, as in the embodiments of the invention shown in' Figs. 5 to 12, may be utilized to release a latch mechanism, such as the mechanism |36 shown in Figs. 5 and 6, to enable fuse 214 to drop out of the circuit in response to blowing of the fuse.

The fuse structures shown in Figs. 15 to 17 are also of the totally enclosed type, which are capable of generating a predetermined pressure within the fuse enclosure upon circuit interruption, and may be mounted to drop out of the associated circuit in the same manner as the fuses shown in Figs. 1 to 3. The particular structures shown in Figs. l to 17, being similar to the structures shown in Figs. 1 to 3, like reference numerals have been used to designate like parts.

In Fig. the fuse reiill unit differs from that shown in Fig. 1 in that it includes a tu` bular metallic member 230, having an internally threaded upper end portion forming in the member 238 a shoulder 232, on which is seated a metallic supporting disk 234 of conducting material. The disk 234 is secured in position in tubular member 23D by means of an end closure plug 236, threadedly engaged in the upper end of tubular member 230, and having a reduced extending through aperture 26 in end terminal cap 9 of fuse tube I8. Projecting portion 238 is threaded to cooperate with the clamping member 28 for securing the rell unit in operative position within the fuse tube.

The lower portion of ltubular member 238 is reduced as at 240 to provide a shoulder upon which is fitted a perforated partition member 2'42. The lower reduced end 240 of the tubular member is threaded into the upper end of an insulating throat member 244, which may be of any desired insulating material, such as fiber or the like. Tubular throat member 244 is provided with a substantially cylindrical bore 246 adjacent to, and forming an extension of the bore in reduced end 240 of tubular member 236. The outer end of throat member 244 is provided with an outwardly ilared exterior portion 248. An insulating tube 250 is positioned in a Central aperture through perforated end closure 242; and extends upwardly within tubular member 238, to a position spaced from supporting -disk 234, for receiving a high-resistance fusible Wire 252 therein. The wire 252, which may be of any desired high-resistance fusible material, such as a nickel-chrome alloy, or the like, has its upper end anchored to supporting disk 234, and its lower end secured in a conducting sleeve 254, which sleeve is, in turn, connected to the upper end of flexible conductor 38.

Within the upper end of tubular member 230, there is provided gas generating material 256 which may be gun powder or similar combustible material, which is adapted to evolve relatively large quantities of gas upon combustion. In the lower portion of tubular member 230, and separated from gas generating material 256, as by a metal screen 258, there is provided cooling means 266, which may be in the form of metal shavings or a gas evolving material which is capable of evolving relatively cool unionized gases when subjected to heat, such for example, as boric acid, fiber, synthetic resins or the like, or a combination of such materials. The sleeve 254 mounted on the upper end of flexible conductor 38 is connected to the reduced portion 240 of the tubular member by means of a short section 262 of a calibrated, relatively low-resistance, fusible wire.

In operation, when the current through the fuse exceeds a value predetermined by the short fusible section 262, this fusible section will melt and the current through the fuse will be transferred to the high-resistance fusible wire 252. Wire 252, in turn, will melt practically instantaneously, and the arc formed will ignite gas generating material 256.

Gases generated by explosive or semi-explosive material usually have a high temperature and, therefore, in passing downwardly through cooling material 260, these gases will be cooled and escape through perforated end closure 242, into passage 246 and thence into the lower end of fuse tube I8. After the high-resistance fuse Wire A252 has melted, the arc will obviously be reestablished between sleeve 254 on the upper end of flexible conductor 38 and the closely adjacent portion 240 of tubular member 230. The gases then, in passing downwardly through the fuse, will pass through this arc and expel the upper end of conductor 38 from passage 246. This action not only extinguishes the arc upon circuit interruption, but builds up pressure in the lower portion of fuse tube I8, which will rise to a predetermined value, since a predetermined amount of combustible material 256 will be consumed, and this pressure will cause outward movement of piston 58 in the same manner as in the embodiment of the invention shown in Fig. 2.

After the fuse has blown, it may be relled in substantially the same manner as the fuse shown in Fig. 1, by merely replacing the refill unit held in position by clamping disk 28. It will be noted that the fuse shown in Fig. 15 is totally enclosed before, during, and after circuit interruption, and that a predetermined force is available for actuating piston member 58 outwardly when the fuse blows, irrespective of the value of current interrupted.

The fuse shown in Fig. 16 is similar to that shown in Fig. 15, except for minor variations.- The tubular member 230 of the rell unit in Fig. 16 is quite similar to that shown in Fig. 15, except that it is provided with an integral per- -forated bottom wall, .having `an linteriorly depending, centrally positioned electrode 264, extending beyond the lower 'end of reduced portion .240 of the vtubular member. :An insulating throat .member 266 'is threaded on extension 240, and the .throat member is provided with a restricted .portion intermediate its ends, which may be 'formed by an insert A268, threadedly vmounted within fthroat member 266. The vinner contour of .the throat member flares outwardly `from -insert 268 to provide `a Venturi passage similar to the passage through throat member l244, .shown inFig. 1-5. Insert Y268 is preferably of some heat resistant material and maybe either of metal or an insulating material. IElectrode 264 is connected to the upper end of conductor 38 by a short calibrated fusible section 210. Electrode 264'is also 'provided with a central, vlongitudinally extending bore in which is reoeivedaninsulating sleeve 212, similar to the tube '250 described .in connection with Fig. 15, for receiving arelatively highresistance fusible strain wire 214. VTubular member '236, in this `embodiment of the invention, contains gas generating Ymaterial 256 and cooling material r266 as inthe embodiment of `theinvention shown in Fig. .15.

The operation o`f the fuse shown in Fig. 16 is much like that described in connection with'the fuse shown in Fig. 115, and, "therefore, will not be repeated in detail. The main difference in operation 'of this fuse resides in the fact that the lgas vblast during circuit interruption is ydlrected :peripherally varound arcing electrode 264. Since the 'are will be drawn between electrode 264 fand sleeve 254 fon the upper end of con-- ductor 38, the .gases will `be directed around ithe electrode264; and then convergethrough the restr-icted portion of the arc passage provided by insert 268, and then may expand outwardly in theiiared portion of the passage, through throat member 1266.

'In Fig. 17 there isiillustrated a fuse, similar to those of Figs. vand 16, but differing 'therefrom inthatthe fuse elements properare remote from the pointat which the are is iin-ally struck and extinguished, -and in that the gases generated also operate to separate the arcing terminals to lengthen lthe arc. Since many of the parts of the :fuse shown in Fig. 17 are identical with the .parts ofthe Jfuse shown in Figs. '15 and 16, .like reference `numerals will be used to vdesignate such like parts.

The fuse rell unit, as in the two previously described embodiments of the invention,1includes a tubular member 230, having gas generating material 256 and cooling means 266 therein. However, inthis embodiment of the invention, an vend closure plug 216 is yprovided for .tubular member 230, and the plug is provided `with an interiorly threaded aperture for :receiving anfinksulating screw .218 for securing lend .fitting 2280 tothe tubular member in insulatedV relation therewith. yrin insulating washer 2x82 is provided .between itting 286 and .closure plug i216 tto e1ectrically isolate .theseiparts Fitting 286 is provided with an integral extension 264, 'adapted'to be received in the opening 26 in end terminal cap 9 for cooperation with --clamping 28, to detachably secure the 4refill `unit Yin l`proper position within :fuse tube I8. Fitting v260 and insulating vscrew A21B 4are provided ywith aligned, substantially central bores for the reception of high-resistance fusible wireZsG, vhaving its upper end secured tothe upper end ofrproje'ction 284 of ytitting "286, land having its lower -endextending Athrough .gas generating material 256 to be secured fto tubular member 236. A calibrated llow-resistance fuse wire section 1288 connects fitting 2260 with Cclosure `plug 216 to `provide a cir- .cuit 4in `parallel with the high-resistance fuse vwire 236. The yreduced lower end 246 ofthe tubular member iis kprovided with an insulating throat member 244, Yand exible conductor 38 has the end Isleeve 254 thereof received 1in an aperture Zin the base `of a generally cup-shaped contact memberiZBll. v.Contact 260 may be formed of Aany desiredresilient conducting material, with the `sides :thereof split 'to provide resilient con-v .tact ringersgfor'engaging the inner walls .of the central bore through extension 240 of tubular member 230; .It will be observed that contact 290 substantially lcloses the gas passage-way l.through-the lower end of tubular member 230 and ,is frictionally 'retained at such a ,position by the :engagement ofthe spring Contact lingers with extension 246.

In operation, the fuse shown in Fig. v17 performs similarly to-tliose illustrated in Figs. 15 and `lo `in Ythat the circuit is rst opened by melting of fusible `asection 288 to thereby ltransfer the current to fusible wire 286. Wire 286 then melts, thereby igniting gas generating material 256, which builds up la :predetermined gas pressure within `tubular member 230. This pressure is predetermined by the amount of ygas generating `material used to be of a valuesuiiiciently high to force cup-shaped terminal 296 downwardly lthrough the passage in extension 246 and insulating throat member 240, to Vinterrupt the circuit in the fuse, and establish a predetermined pressure within the lower portion of fuse tube i8.

It will 'be noted that in the embodiments Vof the invention shown in Figs. 15 to 17, there is disclosed different means for providing a predetermined pressure within a totally enclosed fuse holder, entirely independent of the value'of current interrupted, so that a constant force is provided for movin-g a means, such as Vpiston 58 shown in Figs. 2 and 15, outwardly relative to the iuseholcler, to provide a readily visible indication ofthe blown condition of the fuse at the yexterior thereof. Moreover, such `outward movement of Ypiston 58 may vbe utilized, as in theembodiment of the invention shown-inFigs. 2 and 3 for releasing `a means holding the fuse holder in engagement with line contact terminals rso that the fuse holder will automaticallyl be released from atleast one of its line terminalslto'drop out fof its vassociated-circuit 'in response `to a .circuit interrupting operation.

.'lhe-fusestructures illustrated in Figs. l5 to 17 are more particularly Adescribed and claimed.

per se, in my previously mentioned patent.

In viewrof the lforegoing, .it vwill be apparent that there :is ydisclosed hereiny a plurality of modications of totally enclosed fuses which are adapted to dropout y.of the circuit .in ...response to blowingoic `the fuses and .remain .totally enclosedat all times, before; during, and after interruption occurs within the fuse. In al1 of the modifications of the invention, a, predetermined force is 'available to release the mechanism holdinga dropout `'fuse in circuit, and this force is entirely independent of the value of current in terrupted. All r`ol? the modified 'forms of Vfuses disclosedherein, with' the exception of that shown l in Fig. 1, are normally sealed from the 'atmos-v phere andremainfsealed during'and after blowing of the fuse. Furthermore, at least-the modifica- ,tions of the invention shown in Figs. to 17 may, if desired, be used without dropout mechanisms such as that shown in Figs. 1 to 3, 5 and 6, in which case they will serve to provide a readily visible indication of the blown condition of the fuses. Various meansare disclosed vfor releasing dropout mechanisms to enable the fuse to drop out of the circuit, including piston or diaskilled in the art, that many changes and modi- A cations may be made in these structures with- .'out departing from the broad spirit and scope of this invention. Accordingly, it is desired that the invention be interpreted as'broadly as pos'- sible, and that it be limited only as required by the prior art.

I claim as my invention:

1. In a fuse including a substantially closed fuse tube having a pair of terminals thereon, fusible means connecting said terminals, and means responsive to fusion of said fusible means for creating uid pressure in said tube; the combination of a, supporting lever pivoted intermediate its ends on said tube, said lever having a supporting pivot element adjacent one end thereof, means engaging the other end of said lever for normally preventing movement of said lever, a rigid piston-like member slidably extending through an aperture in a wall of said tube and movable outwardly in response to pressure in said tube for releasing said lever for movement, wherebyupon fusion of said fusible means the `fluid pressure developed in said tube acts to expel said piston-like member.

'2. In a fuse including a substantially closed .fuse tube having a pair of terminals thereon, fusible means connecting said terminals,- and means responsive to fusion of said fusible means for creating fluid pressure in said tube; the combination of a supporting lever pivoted intermediate its ends on said tube, said lever having a supporting `pivot element adjacent one end thereof, means engaging the other end of said lever for normally preventing movement of said lever, a rigid piston-like member slidably extending through an aperture in a wall of lsaid tube and movable outwardly in response to pressure in said tube for releasing said lever for movement, Whereby upon fusion of said fusible means the fluid pressure developed in said tube acts to expel said piston-like member, and stop'nieans on said mem-f berto limit its outward movement. 3. In a fuse including a substantially closed fuse tube having a pair of terminals therein, fusible means connecting said terminals, and means responsive to fusion of said fusible means for creatinguid pressure in said tube; the combination of a supporting lever pivoted intermediate its ends on .said tube, said lever having a supportingpivot element adjacent one end thereof, latch means for preventing pivotal movement 'of said lever with respect to said tube, and means responsive; tQ-the pressure de velopedin said tube upon fusion of said fusible means for releasing said latch means.

4. In a fuse including a substantially closed fuse tube having a pair of terminals therein, fusible means connecting said terminals, and means lresponsive to fusion of said fusible means for creating fluid pressure in said tube; the combination of a supporting lever .pivoted intermediate itsends on said tube, said lever having a supporting pivot element adjacent one end thereof, means engaging the other end of said lever for normally preventing movement of said lever, a rigid piston-like member slidably extending through an aperture in a wall oi said tube and movable outwardly in response to pressure in said tube for releasing said lever for movement, means for releasably supporting said tube in engagement with line contacts including a pivot support for said lever pivot element, and latching means engaging the tube at a .point spaced from said pivot support, whereby upon fusion of said fusible means the pressure developed in said tube forces said piston-like member outwardly to release said lever for movement relative to said tube and pivot support to move said tube relative to said latching means to disengage the same and permit movement of said tube out of engagement with respect to at least one of said line co-ntacts.

5. In a fuse, a substantially closed fuse tube having a pair of terminals, fusible means for striking an arc in said tube, means in said tube capable of supplying predetermined relatively large quantities of gas independent of the current magnitude of said arc, at least a portion of said fusible means positioned to initiate gas evolution by said gas supplying means upon fusion of said fusible means, a supporting lever pivoted intere mediate its ends on said tube, said lever having a supporting pivot element adjacentA one end thereof, means engaging the other end of said lever for normally ,preventing relative movement thereof, a rigid piston-like member slidably extending through an aperture'in a wall of said tube and normally maintained at an inner posi-` tion, said piston-like member being slidable out# Wardly of said tube to release said lever, said pis-A4 ton-like portion positioned in said tube to be sub-2 iected to said evolved gases after their passage through said arc, whereby upon fusion of said fusible means the pressure developed in said tube acts to expel said piston-like portion 'and release said lever irrespective of the current value of said arc;

6. In a fuse, a substantially closed fuse tube having a .pair of terminals, fusible means for striking an arc in said tube, means in said tube' capable of releasing predetermined relatively. large quantities of gas independent of the cur-A rent magnitude of said arc, at least a portion of' said fusible means positioned to initiate gasv evolution by said gas evolving means upon fusion of said fusible means, a supporting lever pivoted? intermediate its ends on said tube, said lever have ing a supporting pivot element adjacent one end.' thereof, means engaging'the other end of said lever for normally preventing relative movementA thereof, a rigid piston-like member slidably extending through an aperture in a wall of said tube and normally maintained at an inner posi-z tion, means for releasably supporting said tubei in engagement with line contacts including a pivot support for said lever pivot element, and latch-z ing means engaging the tube at a point spaced,

from said pivot support, said piston-like portion,

, positionedin said tube to be acted 4en by said evolved gases after their passage through said arc, 'whereby upon fusion of said fusible means the pressure developed` in said tube expels said piston-like member to release saidlever for movement relative to said tube and pivot support, and said tu-be moves rel-ative to said latching means to disengage they same and permit movement of said tube outof engagement with respect to at least one of said line contacts a predetermined time after fusion of said fusible means, and irrespectivefof the current value of said are.

7. In a fuse, a fuse tube having closed ends and spaced terminals thereon, conducting means in said tube connecting said terminals, said conducting means including a lfusible element, means in said tube responsive to fusion of said fusible element for independently releasing a predetermined quantity. of arc extinguishing gas irre-v spective of the current magnitude vof the arc to extinguish the. arc, and pressure-responsive means movably mounted on said tube and exposed to the interior of said tube so as to be moved outwardly 4relative to said tube in response to pressure, built up in said tube by production of said predetermined quantity of gas.

8. In a fuse, spaced line contacts, a fuse tube having closed ends and spaced terminals thereon, releasable means normally maintaining said tube ina position wherein said terminals engage said contacts, respectively, conducting means in said tube connectingr said terminals, said conducting means including a fusible element, means in said tube responsive to fusion of said fusible element for independently releasing a predetermined quantity of are extinguishing gas irrespective of the current magnitude of the arc, and pressureresponsive means movably mounted on said tube so as to be moved outwardly relative to said tube in response to pressure built up in said tube by production of said predetermined quantity of gas to release said releasable means and permit movement of at least one of said fuse terminals away from its corresponding contact.

9. In a fuse including a substantially closed fuse tube having a pair of terminals therein, fusible means connecting said terminals, and means responsive to fusion of said fusible means for creating fluid pressure in said tube; the combination of a supporting lever pivoted intermediate its ends on said tubesaid lever having a supporting pivot element adjacent one end thereof, latch means for preventing pivotal movement of said lever with respect to said tube, means responsive to the pressure developed in said tube upon fusion of said fusible means for releasing said latch means, and said pressure responsive means being movable relative to said fuse tube to release said latch means without opening said tube to the atmosphere.

10. In a fuse including a substantially closed fuse tube having a pair of terminals therein, fusible means connecting said terminals, and means responsive to fusion of said fusible means for creating iiuid pressure in said tube; the combination of a supporting lever pivoted intermediate its ends on said tube, said lever having a supporting pivot element adjacent one end thereof, latch means for preventing pivotal movement of said lever with respect to said tube, a piston member slidably mounted in a cylindrical aperture in said fuse tube so as to be movable in response to pressure developed in said tube upon fusion of said fusible means to release said latch means, and means preventing escape of said piston member from said aperture.

11. In a. fuse, spaced line contacts, a fuse tube having closed ends and spaced terminals thereon, releasable means normally maintaining said; tube in a position wherein said terminals engage said. contacts, respectively, conducting means' in said tube connecting said terminals, said conducting means including affusible element, said fuse tube having a` ilexiblewall portion responsive to fusion of said. fusible meansv to move outwardly relative to said tube without opening said tube, tothe atmosphere, and saidreleasable means positioned to be engaged by said fusion responsive means upon outward movement thereof to release said tube andpermit movement thereof to disengage at least one of said fuse terminals from'its corresponding line Contact,

12. In av dropout fuse, spaced line contacts, a movably mounted. fuse tube having closed ends and spaced terminals thereon, latch means for maintaining said tube in a position wherein said terminals engage said contacts, respectively, conducting means including a fusible element in said tube and connected between said terminals, a plunger member limitedly slidably mounted in an opening in one end wall of said' tube, flexible seals ing means connecting said plunger member to walls of said tube surrounding said opening so that said plunger is movable relative to said tube Without opening said tube to the atmosphere, and means responsive toy fusion of said fusible element for moving said plunger member outwardly to release said latch means and permit ymovement of said tube to disengage at least one of said terminals fromk its corresponding contact.

13. In a. dropout fuse, spaced line contacts, a movably mounted. fuse tube having closed ends and spaced terminals thereon, latch means for maintaining said` tube in a position wherein said terminals engage said contacts, respectively, conducting means including a fusible element in said tube and connected between saidy terminals, a piston member limitedly slidably mounted in a cylindrical opening in one end wall of said tube so as to be movable without opening said tube to the atmosphere, resilient means biasing said piston member outwardly relative to said tube, means normally restraining movement of said piston member under the influence of said resilient means, and means responsive to fusion of said, fusible element to release said piston member for movement to release said latch means and permit movement of said tube to disengage at least one of said terminals from its corresponding contact.

14. 'In a fuse, a fuse tube, end terminal closures for said tube, conducting means including a fusible element in said tube connected between said terminal closures, means movably supported by one of said terminal closures and normally held in a predetermined position by fusible material secured to a heat conducting portion of said one terminal closure, and means located within said tube adjacent said one terminal closure for generating a predetermined amount of heat in response to fusion of said fusible element, to melt said fusible material and release said movable means for movement relative to said tube,

15. In a fuse, a fuse tube, end terminal closures for said tube, conducting means including a fusible element in said tube connected between said terminal closures, means movably supported by one of said terminal closures and normally held in a retracted position by fusible material secured to a heat conducting portion of said one terminal closure, and means located within said tube ad- 19 jacent said one terminal closure for generating a predetermined amount of heat in response to fusion of said fusible element to melt said fusible material and release said movable means for movement away from said tube.

16. In a fuse, a fuse tube, end terminal clo-sures for said tube, conducting means including a fusible element in said tube connected between said terminal closures, outwardly biased means movably supported by one of said terminal closures and normally held in a retracted position by fusible material secured to a heat conducting portion of said one terminal closure, and means located within said tube adjacent said one terminal closure for a predetermined amount of generating heat in response to fusion of said fusible element to melt said fusible material and release said movable means for movement away from said tube. Y Y

1'7. In a fuse, a fuse tube, end terminal closures for said tube, conducting means including a fusible element in said tube connected between said terminal closures, means movably supported by one of said terminal closures and normally held in a retracted position b-y said fusible element, means biasing said movable means outwardly relative to said tube, said one closure having an aperture through which said movable means can move in response to fusion of said fusible element, and exible sealing means connected to said movable element for sealing said closure aperture at all times.

18. In a fuse, a fuse tube, end terminal closures for said tube, conducting means including a fusible element in said tube connected between said terminal closures, means movably supported by one of said terminal closures and normally held in a retracted position in said tube by said fusible element, means biasing said movable means outwardly relative to said tube, said one closure having an aperture through which said movable means can move in response to fusion of said fusible element to a projecting position with respect to said tube, and eXible sealing means connected to said movable element for sealing said closure aperture at all times.

19. In a circuit interrupter, a tubular` fuse holder, a fusible circuit interrupting means in said holder, an actuating member movably mounted at one end of vsaid holder, means normally holding said-member at a retracted posi-V tion, means for causing outward movement of said member, and means responsive to fusion of said circuit interrupting means for releasing said holding means and causing said actuating means to move said member.

20. In a circuit interruptor, a tubular fuse holder, fusible circuit interrupting means in said holder, an actuating member movably mounted at one end of said holder, means independent of said circuit interrupting means normally holding said member at a retracted position. means for causing outward movement of said member, and means responsive to fusion of said circuit interrupting means for causing said actuating means to move said member,

21. In a high Voltage circuit interrupting device having an interrupting element with a fusible section, a plunger, actuating means for said plunger and means operatively connected to said fusible section for causing said actuating means to move said plunger upon the fusing of said section.

22. In a circuit interrupting device having fusible circuit interrupting means, a movable indicating and tripping element, means independent of said interrupting means normally preventing movement of the element, combustible means for destroying said holding means, and means responsive to fusion of said interrupting means for igniting said combustible means.

23. In a fuse, a fuse tube having closed ends and spaced terminals thereon, conducting means in said tube connecting said terminals and including a fusible portion, said tube having an opening at one end, a flexible bellows member se.. cured at one end to said tube about said opening for sealing said opening so that the other end of said bellows member is movable to extended and retracted positions, means dependent upon the continuity of said fusible portion for holding said bellows member at one of its positionsy whereby said bellows member is freed to move to the other of its positions in response to fusion of said fusible portion.

HERBERT L. RAWLINS.

REFERENCES CITED The following references are of record in the iile of this patent:

UNITED STATES PATENTS 

